1. Field of the Invention
The present invention relates to a method for forming a pixel structure, and more particularly, to a method for forming a pixel structure of a transflective liquid crystal display (LCD) device.
2. Description of the Prior Art
Most liquid crystal displays (LCDs) can be categorized into a transmissive type, a reflective type, and a transflective type. The transmissive LCD uses backlight as a source for emitting light. The light emitted by the backlight will pass through the LCD panel to let an observer see the image displayed on the LCD panel. The reflective LCD has a reflective electrode, such as an aluminum electrode. When displaying the image, the ambient light of the reflective LCD will enter the LCD from the observer side of the LCD and then be reflected by the reflective electrode. The reflected light will pass through the surface of the LCD panel again, and finally the observer can see the image displayed on the LCD. The transflective LCD has the characteristic of both transmissive type and reflective type. In other words, each sub-pixel region of the LCD panel comprises a transmission region and a reflection region, where the transmission region uses a backlight as a light source, and the reflection region uses an ambient light as a light source.
Please refer to FIG. 1, which is a schematic diagram of a traditional transflective LCD panel. As shown in FIG. 1, a traditional transflective LCD panel 10 includes an array substrate 20, a color filter substrate 30, and a liquid crystal layer 40 disposed between the array substrate 20 and the color filter substrate 30. The array substrate 20 includes a plurality of pixel regions 22, and each of the pixel regions 22 includes a reflection region 27 and a transmission region 28. For clarity, only one pixel region 22 for example is shown in FIG. 1. The array substrate 20 includes a plurality of thin-film transistors 23 disposed in the reflection regions 27, a plurality of reflective electrodes 24 disposed on the thin-film transistors 23, a dielectric layer 26 disposed between the thin-film transistors 23 and the reflective electrodes 24, and a plurality of transparent pixel electrodes 25 disposed in the transmission regions 28. Both the reflective electrodes 24 and the transparent pixel electrodes 25 are electrically connected to the thin-film transistors 23, so the thin-film transistors 23 can control and drive the pixel electrodes. On other hand, the color filter substrate 30 includes a plurality of color filters 32 disposed corresponding to the pixel regions 22, and a black matrix 34 disposed around the pixel regions 22.
According to processes of forming the traditional transflective LCD device, the traditional method usually takes eight or nine photo mask to define patterns of the elements so as to form a pixel structure of a transflective LCD device. However, every photo mask process for defining patterns should include a plurality of steps, such as deposing, cleaning, lithography, etching, checking, etc, so the processes of forming the traditional transflective LCD device are too complicated. Due to the traditional processes, the output quantity of the LCD devices is quite limited, and it is hard to decrease the cost of forming the traditional transflective LCD device.